Studies that have examined genetic and environmental contributions to measures of family relationships and to associations between family relationships and mental health have found two different patterns of results for adults and children. For children, genetic factors explain most of the covariance between parent-child relationships and child adjustment, while in adults nonshared environmental factors account for most of the covariance between marital relationships and adult adjustment. These different patterns of findings suggest that different mechanisms are involved in linking pertinent family relationships to adjustment in children and adults. The proposed competitive renewal application seeks to extend the Twin Moms Project (R01 MH54610) to include a sample of twin fathers and their families (N=450 twin pairs and their families) and to collect an addition 125 pairs of twin mothers for a sample of 900 twin parents and their families (total N=2,700 individuals). This expanded sample will enable us to examine whether patterns of genetic and environmental influences on associations between family relationships and women's adjustment also hold for men. We will also be able to utilize the full twin families design in an effort to distinguish between different types of genotype-environment correlation for the associations between family relationships and child adjustment. As such, this information will enable us to understand better how and why relationships within the family affect the mental health of family members. We will collect data on family relationships, including parent-child, marital and siblings, on adult and child mental health, and on the individual attributes of family members. We will recruit 450 twin fathers who have at least one biological child from 11 to 20 years of age who resides with them at least half time, has been cohabitating with the same partner for at least 5 years, and whose cotwin also meets the above criterion. Twin parents, their partner and the target child will participate through questionnaires and an interview, using a multi-agent, multi-method strategy. This will enable us to examine the following specific aims: (1) examine the associations between parent-child and marital relationships and the mental health of women and men, (2) examine the associations between parent-child relationships and child mental health and explore possible mediators of these associations, and finally, (3) disentangle genetic, shared environmental and nonshared environmental influences for the associations identified in Specific Aims 1 and 2 using a twin family approach.